Cohorts of 3-6 patients receive escalating doses of samarium Sm 153 lexidronam pentasodium until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. The MTD of samarium Sm 153 lexidronam pentasodium is determined with 2 different doses of bortezomib.